All U.S. patent cited herein are hereby fully incorporated by reference.
Inflatable protective cushions used in passenger vehicles are a component of relatively complex passive restraint systems. The main elements of these systems are: an impact sensing system, an ignition system, a propellant material, an attachment device, a system enclosure, and an inflatable protective cushion. Upon sensing an impact, the propellant is ignited causing an explosive release of gases filing the cushion to a deployed state which can absorb the impact of the forward movement of a body and dissipate its energy by means of rapid venting of the gas. The entire sequence of events occurs within about 30 milliseconds. In the undeployed state, the cushion is stored in or near the steering column, the dashboard, in a door, or in the back of a front seat placing the cushion in close proximity to the person or object it is to protect.
Inflatable cushion systems commonly referred to as air bag systems have been used in the past to protect both the operator of the vehicle and passengers. Systems for the protection of the vehicle operator have typically been mounted in the steering column of the vehicle and have utilized cushion constructions directly deployable towards the driver. These driver-side cushions are typically of a relatively simple configuration in that they function over a fairly small well-defined area between the driver and the steering column. One such configuration is disclosed in U.S. Pat. No. 5,533,755 to Nelsen et al., issued Jul. 9, 1996, the teachings of which are incorporated herein by reference.
Inflatable cushions for use in the protection of passengers against frontal or side impacts must generally have a more complex configuration since the position of a vehicle passenger may not be well defined and greater distance may exist between the passenger and the surface of the vehicle against which that passenger might be thrown in the event of a collision. Prior cushions for use in such environments are disclosed in U.S. Pat. No. 5,520,41 to Bishop; U.S. Pat. No. 5,454,594 to Krickl; U.S. Pat. No. 5,423,273 to Hawthorn et al.; U.S. Pat. No. 5,316,337 to Yamaji et al.; U.S. Pat. No. 5,310,216 to Wehner et al.; U.S. Pat. No. 5,090,729 to Watanabe; U.S. Pat. No. 5,087,071 to Wallner et al.; U.S. Pat. No. 4,944,529 to Backhaus; and U.S. Pat. No. 3,792,873 to Buchner et al.
The majority of commercially used restraint cushions are formed of woven fabric materials utilizing multifilament synthetic yarns of materials such as polyester, nylon 6 or nylon 6,6 polymers. Representative fabrics for such use are disclosed in U.S. Pat. No. 4,921,735 to Bloch; U.S. Pat. No. 5,093,163 to Krummheuer et al.; U.S. Pat. No. 5,110,666 to Menzel et al.; U.S. Pat. No. 5,236,775 to Swoboda et al.; U.S. Pat. No. 5,277,230 to Sollars, Jr.; U.S. Pat. No. 5,356,680 to Krummheuer et al.; U.S. Pat. No. 5,477,890 to Krummheuer et al.; U.S. Pat. No. 5,508,073 to Krummheuer et al.; U.S. Pat. No. 5,503,197 to Bower et al., and U.S. Pat. No. 5,704,402 to Bowen et al. A two-weave construction airbag cushion is exemplified in U.S. Pat. No. 5,651,395 to Graham et al. but does not discuss the importance of narrow basket-weave single fabric layers.
As will be appreciated, the permeability of an airbag cushion structure is an important factor in determining the rate of inflation and subsequent rapid deflation following the impact event. Different airbag cushions are utilized for different purposes. For instance, some airbag cushions are installed within inflation modules for driver protection within the steering column of an automobile. Others are utilized as protection for front seat passengers and are installed in and around the glove compartment and/or on the dashboard in front of such a passenger seat. Still others have been developed in an effort to protect all passengers during a long-duration impact event, such as, for example, a rollover collision. In those types of crashes, the target airbag cushion must inflate quickly under high pressure (such as between about 10 and 40 psi) and remain inflated at a relatively high pressures in order to provide the greatest degree of protection to such passengers. Furthermore, such long-duration airbag cushions preferably comprise "pillow" formations created through the attachment of at least two different fabrics or fabric ends together and sealed, sewn, or the like, together. Upon inflation the free space between the attachment points inflate as well, thereby producing the desired cushioned "pillow" structures. Such long-duration, "pillowed" structures have been disclosed in the prior art as airbag cushions within U.S. Pat. No. 5,788,270 to Halano. However, in order to provide a suitable, effective airbag fabric and cushion comprising two or more points of attachment between fabrics or fabric ends, there has been a need to improve upon the structural integrity of the seams at such attachment points to prevent unwanted and potentially harmful leakage of gas or air from within the target airbag cushion. The prior art has discussed the development of coatings to place over the sewn seams at such attachment points in order to seal the potentially loose portions of such seams and/or to keep the individual yarns of the airbag fabrics at the attachment points stationary in order to prevent yarn shifting and thus possible openings for air or gas leakage. However, such coatings are actually supplemental to the seam structures in providing the necessary barrier to air or gas. A strong, effective, efficient weave construction is the primary method of initially producing an effective airbag fabric for incorporation within an airbag cushion.
Previous attempts have been made at producing inflatable fabrics comprising "pillowed" chambers (such as for side curtains, and the like) which have been produced solely through a weaving procedure and which exhibit reduced air permeability within their weave constructions (in other words, fabrics which are not sewn together to form an inflatable structure). For instance, the closest art appears to be U.S. Pat. 5,011,183 to Thornton et al. which discloses an inflatable fabric structure comprising at least two different areas of differing fabric layers. Patentees discuss two layers of fabric produced by a plain weave and single layer constructions of a plurality of different weave patterns. The interface between the two different fabric layer areas must exhibit at least three different fabric densities (which are dictated by weave constructions), wherein the two looser constructions (double layer plain weave and single layer basket weave) are separated by a tighter construction (single layer plain weave). Such an overall inflatable fabric structure may possess the necessary air permeability characteristics required for proper functioning within a side curtain airbag cushion (particularly upon coating with a standard airbag coating composition); however, the numerous differences in fabric densities also place varying pressures upon discrete areas of the fabric (particularly at or near the interface between the differing fabric layer areas) such that yarn shifting will most likely occur during an inflation event which may produce discontinuities in the integrity of the coating which may in turn compromise the long-term air permeability required for certain airbag applications.
Attempts have been made at improving on such a fabric; however these have led to an increase in the number of different fabric density areas on the fabric, rather than reducing such differing densities. For example, a plain weave construction has been utilized within the double layer area, adjacent to a transition weave pattern, which connects with an Oxford weave pattern, and then either a basket-weave or plain weave construction for the remainder of the single layer area on the fabric. Such a complicated scheme is difficult to produce on a weaving apparatus, as an initial problem. Secondly, the utilization of an Oxford weave zone has been utilized in an attempt to prevent the possibility of weaving in a plain pattern (which is highly undesirable due to the difficulty in manufacturing such high density single-layers fabrics from double-layer amounts of yarn). However, if the area of single layer of fabric is not substantially a straight line, and thus must follow a curved structure, the Oxford weave will eventually become a plain weave for at least that area around such a curved seam. In such an instance, the interface between the two differing layers of fabric will be irregular and invariably produce an undesirable and/or irregular number of floats (i.e., yarns which pass either over or under a certain number of perpendicularly oriented yarns; greater than three such oriented yarns would produce difficulties in preventing yarn shifting, as merely one example). As such, the resultant fabric is itself highly undesirable as a barrier to air permeability, even though coatings may be applied to increase such performance. Thirdly, the individual yarns at the seam between the double and single layer areas, will be placed upon tremendous strain during an inflation event and, as in the Thornton et al. teaching, will most likely result in yarn shifting. With such shifting yarns, the permeability benefits, if any, would, again, most likely be compromised and the produced airbag fabric would not function as required.
To date, there has been no method or fabric structure which has remedied these problems and still can be efficiently woven in a one-step process. A clear need for such an improvement in inflatable fabrics is thus necessary.